Apparatus for heat dissipation and use of such apparatus

ABSTRACT

An apparatus for heat dissipation is provided comprising a heat source, a heat sink and a heat conducting element, wherein the heat conducting element conducts heat energy from the heat source to the heat sink along a heat conducting path, and wherein the heat conducting element is arranged in such a way on the heat source and the heat sink and is configured to physically change in such a way with increasing temperature of the heat conducting element that a) a first cross-sectional area between the heat source and the heat conducting element and/or a second cross-sectional area between the heat conducting element of the heat sink increases, and/or b) a length of the heat conducting path shortens. Further, a video endoscope having such an apparatus and a use of such an apparatus are disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from German patent application 10 2019123 908.7, filed on Sep. 5, 2019. The entire contents of this priorityapplication are incorporated herein by reference.

The present disclosure concerns an apparatus for heat dissipationcomprising a heat source, a heat sink and a heat conducting element. Thedisclosure further relates to the use of such an apparatus for heatdissipation in a videoendoscope.

BACKGROUND

In medical technology, the monitoring and control of temperature andheat, the so-called thermal management, is a great challenge, especiallyfor surgical instruments. Electrical devices and the necessary lightinggenerate heat loss in a confined space, which can only be dissipatedwith considerable design effort due to the constricted conditions.

SUMMARY

It is one object of the present disclosure to provide an apparatus forheat dissipation which ensures a reliable alignment of severalelectronic devices to each other even under constricted spatialconditions. Furthermore, a corresponding use is disclosed.

According to a first aspect, there is provided an apparatus for heatdissipation comprising a heat source, a heat sink and a heat conductingelement, wherein the heat conducting element conducts heat energy fromthe heat source to the heat sink along a heat conducting path, andwherein the heat conducting element is arranged in such a way on theheat source and the heat sink and is configured to physically change insuch a way with increasing temperature of the heat conducting elementthat a) a first cross-sectional area between the heat source and theheat conducting element and/or a second cross-sectional area between theheat conducting element of the heat sink increases, and/or b) a lengthof the heat conducting path shortens. As used herein, the term “heatsource” may correspond to any device associated with a videoendoscopethat generates heat, for example, during operation. Examples of heatsources as described herein may include, but is in no way limited to,light sources, chips, sensors, drives, actuators, electronics, otherelectrical devices, etc., and/or combinations thereof. In someembodiments, the heat source may comprise two or more heat sources(e.g., lights, distal chips, etc.). The heat source may generate heat bypassing electrical current through one or more electrical traces, wires,and/or substrates associated therewith. The term “heat sink” as usedherein may refer to a heat exchanger. The heat sinks, as describedherein, may correspond to thermally conductive materials (e.g., metals,etc.) having a shape or geometry that dissipate heat from the system. Insome embodiments, the heat sinks may be kept continuously at atemperature below the temperature of the heat source and, in some cases,well below this temperature. The heat conducting element may correspondto one or more physical structures, members, arms, fingers, teeth,thermal interface materials, etc. disposed between the heat source andthe heat sink. The heat conducting elements described herein mayfacilitate the transfer of heat from the heat source to the heat sinkalong a controlled path. In some embodiments, the heat conductingelements may comprise thermally conductive materials (e.g., metals,bimetals, etc.) that thermally link the heat source with the heat sink.The heat conducting element transfers heat away from the heat source,for example, in a direction of the heat sink.

The inventors have recognized that there are special challenges in thedissipation of heat from two components which must have an exactposition relative to one another (e.g., especially important for opticalcomponents or lenses arranged in a housing of a videoendoscope, etc.).For example, in the case of heat dissipation the situation exists thatwith known apparatuses heat is dissipated from both devices, but itcannot be guaranteed that the devices remain at least approximately atthe same temperature. Such a temperature difference can be caused, forexample, by the fact that the thermal flow from the first device as heatsource to a corresponding heat sink is different from the thermal flowfrom the second device to the heat sink. Furthermore, it is possiblethat the two devices, even if they are identical in construction, heatup differently. This presents a new challenge, especially inmulti-channel endoscopes or exoscopes, where the optimum alignment andadjustment of two optical channels to each other is also important.

One of the special features is that the heat dissipation is controlledby a passive configuration. The physical principle relied upon here isthat the thermal flow between a heat source and a heat sink increases,the greater the cross-sectional area A of the heat conduction pathbetween the heat source with temperature T₁ and the heat sink withtemperature T₂ and/or the shorter the length d of the heat conductionpath. This physical background is described with the following formula:

$\begin{matrix}{\overset{.}{Q} = {\alpha \cdot \frac{A}{d} \cdot \left( {T_{1} - T_{2}} \right)}} & \;\end{matrix}$

In this context, the cross-sectional area is to be understood inparticular as the effective cross-sectional area and the length inparticular as the effective length. This means that the cross-sectionalarea and/or the length should be considered as those which influence thethermal flow according to the above formula.

Since the apparatus may be made up only of passive elements, it may beused especially in constricted spaces. In addition, the absence ofactive elements enables particularly long trouble-free operation. Ofcourse, it is also possible to equip the apparatus shown with additionalactive components for monitoring and control, such as a temperaturesensor or a temperature control of the heat sink. However, for certainapplications it may be beneficial that the passive embodiment alone mayeffect temperature control.

In principle, the temperature control works as follows. If thetemperature at the heat source rises, the heat conducting element alsoheats up. The physical properties of the heat conducting element,including its spatial configuration, are such that the physical changein the heat conducting element increases the cross-sectional area of theheat conducting path or reduces the effective length of the heatconducting path. Increasing the cross-section and/or shortening theeffective length of the heat conduction path results in an increasedthermal flow from the heat source to the heat sink. This slows down orprevents further heating of the heat source, or reverses it into coolingof the heat source.

When the heat source cools down, the heat conducting element also coolsdown. Due to its physical change, the cross-section of the heatconduction path decreases and/or the length of the heat conduction pathincreases. This reduces the thermal flow from the heat source to theheat sink. In this way, further cooling of the heat source may be sloweddown, prevented or reversed into heating.

Ideally, the materials used and the physical dimensions are selected insuch a way that the heat conducting element already reacts to slighttemperature fluctuations. This makes it possible that the temperature ofthe heat source may be kept at least approximately constant or may bekept within a given tolerance range. Since a further component may inprinciple be cooled with the same apparatus, the heat dissipation at afirst component takes place in principle independently of a cooling ofthe second component, but the apparatus has the effect that bothcomponents are cooled to at least approximately the same temperature.

In some embodiments, temperature control may be achieved by makingselective use of expansions due to temperature changes. This temperaturecontrol keeps the temperature in devices requiring precise positioningat a certain temperature or within a certain temperature range, thusreducing or preventing changes in length due to temperature changes(e.g., due to thermal expansion, etc.) that could alter the positioningor adjustment of these devices.

In some embodiments, the heat conducting element lies planar against theheat source and/or heat sink. Preferably, the heat conducting elementlies with one surface against one surface of the heat source. Inparticular, the surface of the heat conducting element is then arrangedto slide over the surface of the heat source, whereby the two surfacesremain in physical contact even during temperature changes.

In an exemplary embodiment, the heat conducting element has a heat pipefor increasing the heat dissipation or is flowed through by a fluid.

With this embodiment, the thermal flow from the heat source to the heatsink may be increased.

In another exemplary embodiment, the heat source has a first recess inwhich a first section of the heat conducting element is arranged, or theheat conducting element has a first recess in which a first section ofthe heat source is arranged.

This embodiment may make it possible in a constructively simple way toarrange the heat source and the heat conducting element in physicalcontact with each other in such a way that this contact is alwaysmaintained even with temperature changes. The heat conducting elementexpands preferably along the depth of the recess, whereby a planarcontact between the heat conducting element and the heat source on thesides of the recess is continuously maintained. The first recess ispreferably elongated, especially in the form of a prism, a cylinder or acuboid.

In another exemplary embodiment, the heat sink has a second recess inwhich a second section of the heat conducting element is arranged, orthe heat conducting element has a second recess in which a secondsection of the heat sink is arranged.

As described above regarding the first recess in the interaction betweenthe heat source and the heat conducting element, this embodiment alsooffers a good possibility to ensure the continuous physical contactbetween the heat conducting element and the heat sink even at changingtemperatures.

In another exemplary embodiment, the second recess is led through theheat sink and the heat conducting element is led through the heat sinkin the second recess.

With this embodiment, the heat conducting element may also be slid withone surface over the inner surface of the recess of the heat sink. Inaddition, the heat conducting element may now be attached to an abutmentat its end facing away from the heat source.

In another exemplary embodiment, the heat source, the heat sink and theheat conducting element are arranged along a straight line, inparticular along a common longitudinal central axis.

This embodiment may make it easy to establish a physical interactionbetween the heat source, the heat sink and the heat conducting element.In particular, it may be achieved that an expansion of the heat sourceleads to a shortening of the heat conducting element and/or a shorteningof the heat source leads to an expansion of the heat conducting element.

In another exemplary embodiment, the heat source, the heat sink and theheat conducting element are arranged within a housing, wherein a side ofthe heat source facing away from the heat conducting element and/or aside of the heat sink facing away from the heat conducting element isarranged on the housing.

This configuration may provide an abutment for the heat source and/orthe heat sink. In this way, a fixed point may be created for the heatsource and/or the heat sink. Therefore, especially an effect of a changein length of the heat source on the heat conducting element may be welladjusted.

In another exemplary embodiment, an imaging sensor is configured on theside of the heat conducting element facing away from the heat source.This imaging sensor has a line of sight that is directed out of thehousing through an opening in a wall of the housing.

This embodiment may allow the imaging sensor to be kept at asubstantially constant temperature or within a certain temperaturerange. This keeps the line of sight of the imaging sensor essentiallyconstant. Furthermore, when a second imaging sensor forms part of theheat source, or a second imaging sensor forms a second heat source of asecond such apparatus, the first imaging sensor and the second imagingsensor are temperature controlled in a similar manner. This allows thefirst imaging sensor and the second imaging sensor to be kept atsubstantially the same temperature even if they have different heatoutputs.

In another exemplary embodiment, the apparatus further comprises acontrol element which absorbs thermal energy from the heat source andapplies increasing pressure to the heat conducting element as thetemperature rises. As described herein, the control element maycorrespond to a physical structure or member that, when subjected to aparticular temperature, moves from a first position to a secondposition. In some embodiments, the control element may correspond to abimetallic strip, a thermally-expanding metal or combination of metals,or other thermally-activated actuator that mechanically displaces (e.g.,moves, expands, bends, contracts, etc.) when subjected to predeterminedtemperatures or temperature ranges.

This embodiment may make it possible to shorten the length of the heatconduction path between the heat source and the heat sink. This isachieved by the pressure exerted by the control element, whichcompresses the heat conducting element. By shortening the heatconduction path, the thermal flow increases. In this way, heating of theheat source is slowed down, suppressed or turned into cooling. When theheat source cools down, the control element also cools down and thepressure on the heat conducting element is reduced. This causes the heatconducting element to expand in the direction of its original shape, sothat the length of the heat conducting path is now increased. As aresult, the cooling of the heat source is slowed down, suppressed orreversed into a warming.

In another exemplary embodiment, the apparatus has a lever with a firstlever arm and a second lever arm, whereby the control element exertsincreasing pressure on the first lever arm as the temperature rises, sothat the second lever arm exerts a pressure on the heat conductingelement via the heat sink.

This embodiment may make it possible to increase the pressure that thecontrol element indirectly exerts on the heat conducting element. Inexemplary configurations, the ratio of a second length of the secondlever arm to a first length of the first lever arm is at least 1,preferably at least 1.5, particularly preferably at least 2 and inparticular at least 2.5.

In another exemplary embodiment, the apparatus further comprises acontrol element which absorbs heat energy from the heat source, and atleast a section of the control element moves towards the heat conductingelement as the temperature rises or a pressure on the heat conductingelement is increased.

In this embodiment, the control element may act in particular directlyon the heat conducting element. This allows the embodiment to besimplified.

In another exemplary embodiment, the control element is configured as afirst strip and has a counter element which is fixedly arranged as asecond strip on the control element, the counter element being made of amaterial which has a different coefficient of thermal expansion than thecontrol element, the control element being arranged with the counterelement in such a way that the control element presses against the heatconducting element with increasing pressure as the temperature rises.

This embodiment may exploit a physical principle similar to that of abi-metal strip. Since the counter element has a different coefficient ofthermal expansion, especially in the working temperature range of theapparatus, the fixed connection between the control element and thecounter element leads to a deformation of the control element,especially to a curvature. This resulting force is used to exert apressure against the heat conducting element. The pressure compressesthe heat conducting element and the heat conduction path is shortened.In exemplary embodiments, the control element and the counter elementform a bi-metal strip.

In another exemplary embodiment, the heat conducting element isconfigured as a heat conducting pad, the thickness of which decreases asthe pressure exerted by the control element increases.

This embodiment may allow for a robust design. The heat-conducting padmay be compressed as the pressure increases and expands in the directionof its original shape as the pressure decreases.

In another exemplary embodiment, the heat conducting element comprises afirst comb-like element and a second comb-like element configuredcomplementary to each other and meshing with each other, the firstcomb-like element being arranged on the control element and the secondcomb-like element being arranged on the heat sink, the first comb-likeelement and the second comb-like element being further interlocked asthe pressure through the control element increases.

In this embodiment it may be made use of, on the one hand, that thecross-sectional area of the heat conduction path increases the furtherthe comb-like elements are pushed into one another or the further theymesh with one another.

According to another aspect there is provided a videoendoscope with anapparatus according to one of the preceding claims, the heat sourcehaving an imaging sensor. In some exemplary embodiments, the heat sourceis configured as an imaging sensor. In other exemplary embodiments, theheat source is configured as a first imaging sensor and a second imagingsensor or the heat source has a first imaging sensor and a secondimaging sensor. In other exemplary embodiments of the videoendoscope,the videoendoscope has a second apparatus in addition to the firstapparatus mentioned, in which the heat source is configured as a secondimaging sensor.

According to a third aspect, the use of a previously described apparatusfor heat dissipation in a videoendoscope is disclosed.

It is understood that the features mentioned above and the features tobe explained below may be used not only in the combination indicated ineach case, but also in other combinations or in isolation, withoutleaving the scope and spirit of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments according to the disclosure are shown in thedrawings and are explained in more detail in the following description.There is shown:

FIG. 1 shows a first embodiment of an apparatus at a lower temperature;

FIG. 2 shows the first embodiment at a higher temperature;

FIG. 3 shows a second embodiment of an apparatus;

FIG. 4 shows a third embodiment of an apparatus;

FIG. 5 shows a fourth embodiment of an apparatus at a lower temperature;

FIG. 6 shows the fourth embodiment of an apparatus at a highertemperature;

FIG. 7 shows a fifth embodiment of an apparatus at a lower temperature;

FIG. 8 shows the fifth embodiment of a device at a higher temperature;

FIG. 9 shows a sixth embodiment of an apparatus at a lower temperature;

FIG. 10 shows the sixth embodiment at a higher temperature;

FIG. 11 shows a first embodiment of a videoendoscope;

FIG. 12 shows a second embodiment of videoendoscope; and

FIG. 13 shows a third embodiment of a videoendoscope.

BRIEF DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows a first embodiment of an apparatus 10 for heat dissipationwith a heat source 12, a heat sink 14 and a heat conducting element 16.the heat conducting element leads heat energy E along a heat conductingpath 18 from the heat source 12 to the heat sink 14.

The heat conducting element 16 is arranged in such a way at the heatsource 12 and the heat sink 14 and changes physically with increasingtemperature of the heat conducting element 16 in such a way that atleast one of the two following changes results:

-   a) a first cross-sectional area A between the heat source and the    heat conducting element 16 increases and/or a second cross-sectional    area between the heat conducting element 16 and the heat sink 14    increases (not shown here)-   b) a length d of the heat conduction path 18 is shortened.

The heat source 12 has a first recess 20, in which a first section 22 ofthe heat conducting element 16 is arranged. The heat conducting element16 may comprise a material that, when subjected to a particulartemperature or range of temperatures, expands and/or contracts at a ratedefined by an associated coefficient of thermal expansion.

In this first embodiment, the main feature is that the firstcross-sectional area A increases as the temperature rises. In this firstembodiment, the heat conducting element 16 is connected to the heat sink14 via an optional heat conducting pad 24.

FIG. 2 shows the situation when the temperature of the heat source 12and thus also the temperature of the heat conducting element 16increases in the first embodiment according to FIG. 1. It may be seenthat the heat conducting element 16 has extended into the recess 20 ofthe heat source 12. In FIG. 2, the heat conducting element 16 may expand(e.g., in the horizontal direction shown in FIGS. 1 and 2) causing theend of the heat conducting element 16 to further engage the recess 20 ofthe heat source 12 and increase the contact surface area between theheat conducting element 16 and the heat source 12 (e.g., between anouter peripheral surface, or surfaces, of the heat conducting element 16and an internal surface, or surfaces, of the recess 20, etc.) There isstill at least one physical planar contact between the heat conductingelement 16 and the heat source 12.

Since the first cross-sectional area A between the heat source 12 andthe heat conducting element 16 has now increased, there is also a largerthermal flow between the heat source 12 and the heat sink 14. In otherwords, the heat source 12 is now cooled more strongly, or quickly (e.g.,as thermal flow increases so does the transfer of heat).

FIG. 3 shows a second embodiment of an apparatus 10. Here and in thefollowing, reference signs already introduced for the same orfunctionally similar elements are used and not explained again.

In the second embodiment, the heat conducting element 16 has a heat pipe26 to increase heat dissipation. Alternatively, a fluid may also flow(not shown) through the heat conducting element 16. The heat sink 14here has a second recess 28, in which a second section 30 of the heatconducting element 16 is arranged. Specifically, the second recess 28 isled through the heat sink 14, and the heat conducting element 16 ispassed through the heat sink 14 in the second recess 28.

In contrast to the first embodiment, the heat conducting element 16 heredoes not have a heat conducting pad 24. Instead, the heat conductingelement 16 is arranged here on a static abutment 32, which is to beunderstood as immovable even in case of a temperature change withrespect to the heat source 12, the heat sink 14 and the heat conductingelement 16.

FIG. 4 shows a third embodiment of the apparatus 10, whereby here theheat source 12, the heat sink 14 and the heat conducting element 16 arearranged along a straight line, in particular along a commonlongitudinal central axis 34. The heat source 12, the heat sink 14 andthe heat conducting element 16 are here arranged within a housing 36,whereby a side 38 of the heat source 12 facing away from the heatconducting element 16 and/or a side 40 of the heat sink 14 facing awayfrom the heat conducting element 16 is arranged on the housing 36.

Here, the heat conducting element 16 is configured as a compressibleheat conducting pad. When the heat source 12 heats up and expands (e.g.,in an axial direction along the line of sight 44, etc.), the heat source12 compresses the heat conducting element 16, thus shortening the lengthd of the heat conducting path 18 (e.g., in the axial direction). In thisway, the thermal flow from the heat source 12 to the heat sink 14increases, so that the heat source 12 is cooled more strongly as thetemperature rises. When the heat source 12 cools and shrinks, the heatconducting element 16 expands again, increasing the length d of the heatconduction path 18. In this way, the thermal flow from the heat source12 to the heat sink 14 decreases, so that the heat source 12 is cooledless as the temperature decreases. As described herein, the shorter thelength d of the heat conducting path 18, the quicker the transfer ofheat. Additionally or alternatively, the longer the length d of the heatconducting path 18, the longer, or slower, the transfer of heat.

In this third embodiment, an imaging sensor 42 is arranged on the side38 of the heat source 12 facing away from the heat element 16. Theimaging sensor 42 has a line of sight 44 which is directed out of thehousing 36 through an opening 46 in a wall 48 of the housing 36.

FIG. 5 shows a fourth embodiment in which the apparatus 10 also has acontrol element 50 which absorbs heat energy from the heat source 12 andexerts increasing pressure on the heat conducting element 16 as thetemperature rises. As explained above, this causes the elastic heatconducting element 16 to be compressed as the temperature rises, thusshortening the length d of the heat conducting path 18. While thecontrol element 50 of FIG. 5 and FIG. 6 is illustrated as a bar disposedbetween the heat source 12 and the lever 52, it should be appreciatedthat the control element 50 may correspond to any physical structure ormember that, when subjected to a particular temperature, moves from afirst position to a different second position. In some embodiments, thecontrol element 50 may correspond to a thermally-expanding metal orcombination of metals, or other thermally-activated actuator thatmechanically displaces (e.g., moves, expands, bends, contracts, etc.)when subjected to predetermined temperatures or temperature ranges. Inone embodiment, the control element 50 may mechanically displace solelythrough thermal expansion. Stated another way, the control element 50may not include any moving parts, actuators, pistons, motors, or othercomponents other than a construction, shape, and/or arrangement of thephysical structure making up the control element 50.

In the fourth embodiment, a lever 52 is used for this purpose, which hasa first lever arm 54 and a second lever arm 56. Here the lever 52 isarranged on a lever abutment 58. As the temperature rises, the controlelement 50 exerts increasing pressure on the first lever arm 54 so thatthe second lever arm 56 exerts pressure on the heat conducting element16 via the heat sink 14. Stated another way, as the control element 50increases in temperature, the control element 50 increases in size(e.g., due to thermal expansion, etc.). More specifically, as thetemperature increases, the control element 50 extends in a lengthdirection from the heat source toward the first lever arm 54 of thelever 52. This increase in length moves the first lever arm 54 towardthe lower abutment 58 and as the lever 52 pivots about a fulcrum 53, orpivot point, the second lever arm 56 moves away from the lower abutment58 (e.g., in a direction toward the heat sink 14). The pressure from thesecond lever arm 56 is transmitted here (e.g., to the heat sink 14,etc.) by a rigid rod 60 as an example.

FIG. 6 shows the situation with the fourth embodiment when the heatsource 12 has heated up and the control element 50 has expanded as aresult. It may be seen that the control element 50 has pressed againstthe first lever arm 54, whereby the second lever arm 56 has pressed theheat sink 14 towards the heat source 12 via the rod 60. Due to thepressure, the heat conducting element 16 is compressed, so that thelength d of the heat conducting path 18 is shortened between anuncompressed state (e.g., as shown in FIG. 5) and the compressed state(e.g., as shown in FIG. 6).

FIG. 7 shows a fifth embodiment in which the apparatus 10 also has acontrol element 62 which absorbs heat energy from the heat source 12 andat least a section of the control element 62 moves towards the heatconducting element 16 as the temperature rises or increases pressure onthe heat conducting element 16.

In this fifth embodiment, the control element 62 is configured as afirst strip 64 and also has a counter element 66 which is fixedlyarranged as a second strip on the control element 62. The controlelement 62, as described herein, may correspond to a bimetallic stripthat converts temperature changes into mechanical displacement. Thefirst strip 64 and the counter element 66 of the control element 62 maybe made from different materials. The counter element 66 is made of amaterial that has a higher coefficient of thermal expansion than thefirst strip 64 of the control element 62. For instance, when the firststrip 64 is made from first material (e.g., steel, carbon fiber, etc.)having a first coefficient of thermal expansion, the counter element 66may be made from a second material (e.g., copper, aluminum, etc.)material having a greater, or higher, second coefficient of thermalexpansion. The control element 62 is arranged with the counter element66 in such a way that the control element 62 presses against the thermalelement 16 with increasing pressure as the temperature rises. Forinstance, as the temperature of the heat source 12 increases, heattransfers (e.g., through a conduction path, etc.) from the heat source12 to the first strip 64 and the counter element 66 of the controlelement 62. Because the counter element 66 has a higher coefficient ofthermal expansion than the first strip 64, the counter element 66increases in length at a greater rate than the first strip 64. Thisdifference causes a portion of the control element 62 (e.g., the endopposite the connection to the heat source 12, etc.) to mechanicallydisplace, or bend, in a direction toward the heat sink 14 (e.g.,compressing the heat conducting element 16, as shown in FIG. 8). In someembodiments, this mechanical displacement may be referred to herein as acantilevered beam deflection.

An inverse arrangement is also possible, in which the positions ofcontrol element 62, i.e. the first strip 64, and the counter element 66are reversed. The counter element 66 is then made of a material that hasa lower coefficient of thermal expansion than control element 62, forexample carbon.

FIG. 8 shows the situation with the fifth embodiment when thetemperature of the heat source 12 has increased and the control element62 has compressed the heat conducting element 16. In this embodiment,heat conducting element 16 is preferably configured as an elastic heatconducting pad, the thickness of which decreases as the pressure fromcontrol element 62 increases.

FIG. 9 shows a sixth embodiment, in which a control element 62 with acounter element 66, as described in FIG. 7, is used.

In the sixth embodiment, the heat conducting element 16 has a firstcomb-like element 68 and a second comb-like element 70, which areconfigured complementary to each other and comb together. Stated anotherway, the teeth of the first comb-like element 68 may intermesh with theteeth of the second comb-like element 70. In some embodiments, the firstcomb-like element 68 and the second comb-like element 70 may be referredto as combs having alternating teeth and hollows. The teeth and hollowsmay offset between the first comb-like element 68 and the secondcomb-like element 70 such that the teeth of the first comb-like element68 align and engage with the hollows of the second comb-like element 70and/or vice versa. Like the control element 62 of FIGS. 6-10, the teethof the heat conducting element 16 (e.g., of the first comb-like element68 and the second comb-like element 70) may be made from a thermallyconductive material. The first comb-like element 68 is arranged at thecontrol element 62 and the second comb-like element 70 is arranged atthe heat sink 14. As shown in FIG. 10, the first comb-like element 68and the second comb-like element 70 push further into each other as thepressure through the control element 62 increases, i.e. as thetemperature of the heat source 12 rises. As the temperature of the heatsource 12 rises and the counter element 66 is caused to expand, orincrease in length (e.g., running in a horizontal direction shown in thefigures, etc.), the control element 62 mechanically displaces, or bends,in a direction toward the heat sink 14 (e.g., providing a greatersurface contact, or contact area, between the teeth of the firstcomb-like element 68 and the teeth of the second comb-like element 70,etc.).

FIGS. 11-13 show various embodiments of a videoendoscope 80 capable ofemploying any one or more of the heat conducting elements 16 and/orarrangements between the heat sources 12 and the heat sinks 14 asdescribed in FIGS. 1-10. FIG. 11 shows a first embodiment of avideoendoscope 80. In a housing 36 a heat source 12 is arranged here,which has an imaging sensor 42, a heat sink 14 and a heat conductingelement 16.

FIG. 12 shows a second embodiment of a videoendoscope 80, where the heatsource 12 has a first imaging sensor 42 and a second imaging sensor 42′.

FIG. 13 shows a third embodiment of a videoendoscope 80, which has afirst heat source 12 with an imaging sensor 42 and a second heat source12′ with a second imaging sensor 42′. In addition to the first heatconducting element 16, a second heat conducting element 16′ is alsoshown here.

What is claimed is:
 1. An apparatus for heat dissipation comprising aheat source, a heat sink and a heat conducting element, wherein the heatconducting element conducts heat energy from the heat source to the heatsink along a heat conducting path, and wherein the heat conductingelement is arranged in such a way on the heat source and the heat sinkand is configured to physically change in such a way with increasingtemperature of the heat conducting element that at least one of a) afirst cross-sectional area between the heat source and the heatconducting element increases, b) a second cross-sectional area betweenthe heat conducting element of the heat sink increases, or c) a lengthof the heat conducting path shortens.
 2. The apparatus of claim 1,wherein the heat conducting element has a heat pipe for increasing theheat dissipation or is flowed through by a fluid.
 3. The apparatus ofclaim 1, wherein the heat source has a first recess in which a firstsection of the heat conducting element is arranged.
 4. The apparatus ofclaim 1, wherein the heat conducting element has a first recess in whicha first section of the heat source is arranged.
 5. The apparatus ofclaim 1, wherein the heat sink has a second recess in which a secondsection of the heat conducting element is arranged.
 6. The apparatus ofclaim 1, wherein the heat conducting element has a second recess inwhich a second section of the heat sink is arranged.
 7. The apparatus ofclaim 5, wherein the second recess is led through the heat sink and theheat conducting element is led in the second recess through the heatsink.
 8. The apparatus of claim 1, wherein the heat source, the heatsink and the heat conducting element are arranged along a straight line.9. The apparatus of claim 1, wherein the heat source, the heat sink andthe heat conducting element are arranged along a common longitudinalcentral axis.
 10. The apparatus of claim 1, wherein the heat source, theheat sink and the heat conducting element are arranged within a housing,wherein a side of the heat source facing away from the heat conductingelement is arranged on the housing.
 11. The apparatus of claim 1,wherein the heat source, the heat sink and the heat conducting elementare arranged within a housing, wherein a side of the heat sink facingaway from the heat conducting element is arranged on the housing. 12.The apparatus of claim 10, wherein on the side of the heat source facingaway from the heat conducting element an imaging sensor is configured,which has a line of sight which is directed out of the housing throughan opening in a wall of the housing.
 13. The apparatus of claim 1, theapparatus further comprising a control element that receives thermalenergy from the heat source and exerts increasing pressure on the heatconducting element as the temperature rises.
 14. The apparatus of claim13, the apparatus comprising a lever with a first lever arm and a secondlever arm, the control element adapted to exerting an increasingpressure on the first lever arm as the temperature rises, so that thesecond lever arm exerts a pressure on the heat conducting element viathe heat sink.
 15. The apparatus of claim 1, wherein the apparatusfurther comprises a control element which receives heat energy from theheat source and at least a section of the control element moves towardsthe heat conducting element or increases pressure on the heat conductingelement as the temperature rises.
 16. The apparatus of claim 13, whereinthe control element is configured as a first strip and has a counterelement which is fixedly arranged as a second strip on the controlelement, the counter element being made of a material, which has adifferent coefficient of thermal expansion than the control element,wherein the control element is arranged with the counter element in sucha way that the control element presses against the heat conductingelement as the temperature rises with increasing pressure.
 17. Theapparatus of claim 16, wherein the heat conducting element is configuredas a heat conducting pad, the thickness of which decreases as thepressure through the control element increases.
 18. The apparatus ofclaim 16, wherein the heat conducting element comprises a firstcomb-like element and a second comb-like element configuredcomplementary to each other and meshing with each other, wherein thefirst comb-like element is arranged on the control element and thesecond comb-like element is arranged on the heat sink, wherein the firstcomb-like element and the second comb-like element continue to slideinto each other as the pressure through the control element increases.19. A video endoscope, comprising: a heat source comprising an imagingsensor; a heat sink; and a heat conducting element, wherein the heatconducting element conducts heat energy from the heat source to the heatsink along a heat conducting path, and wherein the heat conductingelement is operatively connected to the heat source and the heat sinkand mechanically displaces from a first heat transfer position to asecond heat transfer position when a temperature of the heat conductingelement increases to a predetermined temperature, and wherein in thesecond heat transfer position at least one of a) a first cross-sectionalarea between the heat source and the heat conducting element isincreased over the first heat transfer position, b) a secondcross-sectional area between the heat conducting element and the heatsink is increased over the first heat transfer position, or c) a lengthof the heat conducting path is shortened from the first heat transferposition.
 20. A method of dissipating heat in a video endoscope,comprising: providing a video endoscope comprising an image sensor,wherein the image sensor corresponds to a heat source of the videoendoscope; providing a heat transfer apparatus, comprising: a heat sink;and a heat conducting element, wherein the heat conducting elementconducts heat energy from the heat source to the heat sink along a heatconducting path, and wherein the heat conducting element is operativelyconnected to the heat source and the heat sink and mechanicallydisplaces from a first heat transfer position to a second heat transferposition when a temperature of the heat conducting element increases toa predetermined temperature, and wherein in the second heat transferposition at least one of a) a first cross-sectional area between theheat source and the heat conducting element is increased over the firstheat transfer position, b) a second cross-sectional area between theheat conducting element and the heat sink is increased over the firstheat transfer position, or c) a length of the heat conducting path isshortened from the first heat transfer position.